Combustion device



Aug l, 1944- o. A. oHLssoN COMBUSTION DEVICE Filed Dec. 19, v1939 2 Sheets-Sheet l Aug- 1 1944- o. A. oHLssoN COMBUSTIN DEVICE A 2 sneaks-sheet "2 Filed Deo.

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@g/f [5c u i Patented Aug. l, 1944 UNITED STATES PATENTTOFFICE Application December 19, 1939,*Seral' No. y310,041

Inv Sweden May 17', 1939 s claims. (el.` 11u-31) i f Hitherto it has been a diicult problem to burn solid high gas-yielding fuels such as coal, brown coal, peat, wood, chips or the like in an economical manner. Usually, small fireplaces are vcombined with a fuel magazine to facilitate the r` ing work but in arrangements of this kind itis difficult to control the distillation of the fuel so thatv the quantity of -gas required for a predetermined quantity of heat corresponds to the supplied quantity of air. Owing to this. fact re1- atively expensive low gas-yielding fuels such as coke are usually used for small magazine fireplaces. Again, in larger fireplaces it is diiilcult to a achieve a good mixing of the combustible gases and the air so as to bring the combustion to an end within a reasonably large combustion chamber. These disadvantages have resulted in an actual need of improved combustion devices for solid high gas-yielding fuels.

The main object of the present invention is to bring about an improvement of this kind.

A further object of the invention is to effect a complete combustion and favourable Working conditions by combining a gasiiicationvchamber generating producer gas and having a grate for the supply of air with a mixing and ignition. chamber (or more such chambers) having an opening or more openings to the gasification chamber and serving to mix the gases with air and to ignite the mixture so that the final coinbus-tion iseffected in a fire box. or the like arranged after the mixing and ignition chamber.

A further object of the invention is to keep the height of the layer of the burning fuel ap-` proximately constant by providing for approximately constant distance between the grate and the upper portion of the gasification chamber in operation. To this purpose I prefer to arrange the mixing and ignition chamber Wholly` or partly in the gasication chamber or in direct communication therewith, for instance between the gasification chamber and the fuel magazine or in a pocket or the like, which communicates with the gasication chamber and which at least on one side is bounded by the fuel falling or sliding down into the gasification chamber.

A still further object of the invention is to keep the composition of the gases approximately constant. This result is gained by keeping constant the height of the burning fuel in the manner described and by providing for substantially constant supply of secondary air to the mixing and ignition chamber through one or moregair inlets in or near to one end of the said chamber.

Still' another object of the invention is to cause the pieces of fuel to` fall or slide in a predetermined manner so as toform a;` free fuel surface close to the opening orv openingsY of the mixing and ignition chamber in the gasification chamber by providing a constriction, shoulder, screen means or the like between the fuel magazine and the gasicationchamber. The mixing and ignition chamber may be arranged in the mass of fuel "in such a manner that. it forms itself the said constriction or screen. A further object of' the invention is to effect an ejector action with accompanying vacuum of practically constant value in the mixing chamber and the gasification chamber.

' Moreover, an object of the invention is to provide means for Aoperating the combustion device intermittently' at constant load and to facilitate the removal' of ash. y

Further objects and features of the invention will bedescribed. in the following specification with reference to the accompanying drawings, in which: Y v Figures I and 2`i1lustrate an embodiment of the invention in vertical sections', Figure 1 being takenv transversally on thelines I-I in Figure 2, and Figure 2 being taken on the line II-II in Figure 1; g

Figures 3 and 4 are similar sections of a further embodiment; j

Figures 5 and 6 are similar sections of a further embodiment, Figure 5 being taken on the line 'Vl--V' in Figure 6,` and Figure`6 being takenA on the line VI--VI in Figure 5 ;A

Figures 7 and' 8 are fsim'ilar sections of a further embodiment;

Figures 9 and 10 are similar sections of a further embodiment, and

Figure 1I is a vertical section ,of stilla further embodiment vvof' the invention.`

f' All figures arediagrammatical and merely show particulars with which. the invention is concerned. In all gfuresthe same reference characters. indicate the same parts. 4

.v With referenceto Figures 1 and 2 the fuel. magazine I communicates with the gasificationl magazine, the chamber 4 etc. may be provided Y with water jackets Il communicating with some heating system. Preferably, the interior o f the chamber 4 and the air inlet 6 is lined witlf'refractory material.

Solid fuel filled into the magazine rests on the practice, the combustion is very similar to that of oil in an oil burner in that the incompletely burnt gases escaping at the end l2 of the chamber 4 are completely burnt with a bright iiame iri the iiame chamber or iire box F.

A very suitable and economical operation is accomplished if the fireplace or combustion device described is constructed to operate intermittently at constant load during periods the duration of which is determined by the mean requirement of heat. During the stand-still periods the supply of air through the inlet 6 is closed and the supply of primary air through the valve l0 is restricted so as to maintain a very slow fire (glowing fuel). This control may be effected automatically through impulses acting in degrates 1 so as to surround the tubularchamber,

channel or duct 4 which screens the gasification Y chamber from a part of the fuel in the magazine.

Inthe passages 3 on both sidesof the chamber 4 the fuel falls or glides down forming free fuel surfaces adjacent to the opening or slot 5, which extends longitudinally of the chamber 4 and preferably has a relatively large width circumferentially of the chamber.

The air 4inlet 6 is connected toblower means indicated at 6a (say afan) for injecting air under pressure into the inlet which in the embodiment shown is shaped so as to produce ejector action and consequently a vacuum of practically constant value in the chamber 4 and the gasification chamber 2 communicating therewith through the opening or slot 5.

Inope'ration the supply of air to the grates l is adjusted so as to effect generation of producer gases in the gasification chamber 2. Due to the ejector action of the air entering the chamber 4 through the inlet or ejector 6 thje producerfgases generated from the fuel-in thefg'asication chamber are drawn into theV chamber 4, mixed intimatelywith the air from the inlet or ejector 6 and ignited. The supply of vair through the in -A let 6 is controlled in such a manner in relation'to the productionV of gases and Vthe supplyof air .A

through the grates, that the 'gas mixtureforced at great'v'elocity through the chamber 4 is' not burnt completely within this chamber but the iinal and complete combustion of the mixture escaping at the end l2 of the chamber A4v takes place in a fire box or ame chamber diagrammaticallyV indicated at F in Figure 2 and arranged directlyafter the chamber 4. A'part'of the air fromv the ejector 6 willv sweep `over the surface of the glowing fuel adjacent to the opening 5, thus activating the combustion'and improving the mixing action.

According as the combustion proceeds new fuel glides down into the gasification chamber 2, and

ash is separated through the space between thegrates. It is very important that the surface of the grates and of the spaces therebetween is lsufciently large, i. e. relatively large in relation'to the load of the grate so as to prevent formation of slag and to avoid ash and cokeparticles yflying with the stream of gases through the layer of fuel,

As the height or'thick'ness ofthe burning fuel layer is kept approximately constant due to the constant distance between' the chamber 4 and the grates the producer gases have practically constant composition providedthat the valve l0 and the ejector 6 supply 'a substantially constant quantity of air. The combustion proceeds veryf uniformly as the composition ofthe 'gases fand, alsothe draught is constantgapproximately. 'In' ,pendence of the temperature or the pressure in a heating system connected to the replace or the like. Often it may be favourable to admit the supply of air through the ejector 6 to the chamber 4 after the valve Hl is opened so that when' it is intended to increase the heat from slow iireto maximal load, the supply of primary air to the grates is started earlier than the ejector 6, but when it is intended to decrease the heat maximal load to slow re the supply of primary vair is reduced or closed earlier'than the ejector. Thus, in the former case the production of gas is initiated before the ejector is started whereby harmful excess of air in chamber 4 is avoided. On the other hand, the ejector will continue to work for some time after the primary air tothe grates has been closed for slow fire so as to secure thensupply of suiiicient quantity of secondary air for the combustion of the gases in the chamber 4 as long as the fire still is hot. During the slow-fire periods it is only necessary to supply so much primary air to the grates that the lire barely is kept'alive, while the fan for lio the airA inlet 6 may be closed completely.

It is also possible to connect the fan 6a with the valve l0 so that the fan supplies air both tog'the ejector 6 and to the grates 1. For this case: one or two valves may be arranged to control the, supply of air tothe ejector and to the grates respectively.

The' arrangement according to Figures 3 and i (differsrfrom that shown in Figures 1 and 2 insofar as the`constriction 3 is formed by the sloping walls la, |a of the fuel magazine I. The grates l are curved, for instance approximately semi-circular, and form together a basket-like grate opened at the top and the bottom, Preferably, the curved grate b'ars 1 are arranged to be adjusted, for instance by being swung around axes la; which may be operated from the outside of Athe fireplace so as to approach and separate the' grate bars from one another. Under the iniiuence of this action, which is effected with' predetermined intervals of time, the fuel is prevented from catching in the gasification chamber 2,

and ash and refuse of fuel may easily be removed.`

the interior of the basket-like grate L1.'

In Figures 5 and 6 a portion (dsaytherv middle part) of the chamber 4 is arranged in a pocketb bounded on two sides by the walls Ib and Irc and on the third side bythe free ysurface 5av of'fuel which is caused to glide downwards at a predetermined angle due to the constriction 3 formed' In this embodiment the chamber 4 is located bythesloping wall Id of the fuel magazine.' At

one end the pocket now described communicates with' the inlet 6 and at the other end with the tubular chamber 4. 'Communication' Withlthe gasication chamber 2 is effected through the free.'

`chimney from the device,

case only one `'grate 'l needbeprovided. According-to `Figur-es 7 and 8 the constriction `3 visfor'med substantially'in the same manner as vin Figures 3 and 4. The fuel glides downwardly vand uncovers an annular chamber or a pocket c at vthe top of the gasification chamber 2. The

chamber 5c communicates with the-chamber 4v `of .a rotatable shaft I3 and a gear 13a. In operation the g-rate is rotated, Vwhereby the refuse of fuel may be removed continuously by means `of a scraper. The middle portion -of the chamber 4 is constituted .by a space bounded yby vvall,` le

and the free. surface of .fuels exposed at the opening 5. Also in Figure l1 the grate 'l-b is rotatable Vby means of a screw |3b and a worm wheel l3c rotating the shaft 1c. In this embodiment'the air inlet 6 and a part of the chamber 4 is vertical and the constricticns 3 are formed between the latter chamberl andthe vertical walls I f of the fuel magazine l. The rotating shaft 1c of the grate is hollow and serves to supply air to the inlet B. The inlet 6 and the chamber 4 may be arranged to incline in any other manner.

In al1 embodiments the constricted passages 3, should be dimensioned so as to prevent the fuel from getting caught.

Primarily the device described is intended to be used as an additional aggregate for boilers, particularly for central heating furnaces or theflike, in which case the chamber 4 is connected to the fire box or the flame chamber of the boiler or the furnace, preferably similarly to an oil burner. If it is desired to use the device for old boilers merely a slight modification of the front plate of the boiler is necessary. The device according to the invention may be used for any high gasyielding, solid fuel and may be adapted for any requirement of heat.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, as defined by the following claims, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. Thus it is not necessary to supply air under pressure to the air inlet 6 but the air may be drawn through this inlet and through the grates by means of a suction apparatus arranged in the The air flowing through the air inlet may be divided into a plurality of small jets, for instance arranged coronarily.

What I claim is:

l. A combustion device comprising in combination means defining a fuel receptacle for solid fuel; means defining a gasification chamber to generate producer gas adjoining and below said fuel receptacle; means dening a constricted conduit interconnecting said fuel receptacle and gasification chamber and through which fuel passes from the former to the latter; a duct for the collection of producer gas from the gasification chamber and constituting the ignition chamber for such gases, said duct being arranged intermediate said fuel receptacle and gasification chamber and having a passageway interconnecting said gasification chamber withthexinterior of said duct; `supporting means in saidsgasifcaltion chamberxinpart atflleastfbelow said `duct and on the side of the latter whichis provided with saidpassageway, for supporting' in said gasification chamber, between said suporting. means and said passageway, fuel fed from said-fuel receptacle through said constricted conduit; said duct having an exit opening at the rear end thereof and means at the'v front end thereof for injecting air under pressure into and through said duct, and said passageway being arranged intermediate the exit end and the front end of 'said duct. J 1 2; Acombustion device comprising incombination a casing defining afuel receptacle for solid fuelandla gasification chamber, said chamber forming .1a-,continuation of the said fuel receptacle and being arranged therebelow, wherebyffuel fromthe'former maybe fed to thelatter; means for 'supplying primaryl air to the gasification chamber to generate producer gas therein;: a duct d'eninga gas collecting and igniting chainber, said duct being `arranged within said casing intermediate said fuel receptacle and said chamber, said duct having an air inlet at thefront end thereof and an exitat the rear-end thereof-and 'a passageway interconnecting the interior there:` of with the gasification chamber, said passageway being positioned intermediate said front and rear ends; supporting means in said gasification chamber, below said duct and on the side of the latter which is provided with said passageway, for supporting in said gasification chamber, between said supporting means and said passageway, fuel fed from said fuel receptacle; and means for injecting air under pressure to and longitudinally through said duct. Y

3. A combustion device comprising in combination means defining a fuel receptacle for solid fuel; means defining a gasification chamber to generate producer gas adjoining and below said fuel receptacle; means defining a constricted conduit interconnecting said fuel receptacle and gasification chamber and through which fuel passes from the former to the latter; a duct for the collection of producer gas from the gasification chamber and constituting theignition chamber for such gases, said duct being arranged intermediate said fuel receptacle and gasification chamber and having a passageway interconnecting said gasification chamber with the interior of said duct; supporting means in said gasification chamber, below said duct and on the side of the latter which is provided with said passageway, for movably supporting in said gasification chamber, between said supporting means and said passageway, fuel fed from said fuel receptacle through said conduit; said duct having an exit opening at one end thereof and an air nozzle inlet at the opposite end thereof, and means to supply air at high velocity to the said air nozzle.

4. A combustion device comprising in combination means defining a fuel receptacle for solid fuel, means defining a gasification chamber to generate producer gas adjoining and below said fuel receptacle; means defining a conduit interconnecting said fuel receptacle and gasification chamber and through which fuel passes from the former to the latter; a substantially horizontal gas collecting duct arranged in said conduit intermediate the fuel reecptacle and the gasification chamber so as to screen a part of the latter from the fuel in the said receptacle, said duct having an air inlet at one end thereof and an exitv openingat the opposite end thereof, an intermediate portion between the 'ends of the duct being open to thev gasification chamber to collectgases therefrom; Van upwardly and outwardly inclined supporting grate in said; gasification chamber, below said duct and on the side of the intermediate opening thereof, fonsupfA porting in said gasification chamber, between said grate and said intermediate opening, fuel fed from said fuel receptacle; and jet means for supplying air under pressure to said air inlet.

5. A combustion device comprising in combif nation means defining a fuel receptacle for solid fuel, means defining a gasification chamber to generate producer gas adjoining and below said fuel receptacle; means deningfa conduit interconnecting said fuel receptacle and` gasification chamber and through which fuel passes fromthe former to the latter; a substantially horizontal gas collecting duct arranged in said conduit in termediate the fuel receptacle and the gasification chamber so as to screen a part of the latter from the fuel in the said receptacle, Asaid duct having an air inlet at one end thereof and an exit opening at the opposite end thereofyan intermediate portion between the ends of the duct being open to the gasification chamber to collect gasestherefrom; upwardly and outwardly inclined supporting grates in said gasification chamber, below said-duct and on theside of the intermediateopening thereof, for supporting in said gasification chamber, between said grates and said intermediate opening, fuel fed from said fuel receptacle; and jet means for supplying air under pressure to said air inlet.

6. A combustion device comprising in combination means defining a fuel receptacle for solid fuel; means defining a gasification chamber adjoining and below said fuel receptacle; means dening a constricted conduit interconnecting said fuel receptacle' and gasification chamber and'through which fuel passes from the former to the latter; inclined supporting means in the lower part of said gasification chamber and in substantial alinement with said conduit, for supporting in said gasification chamber the fuel fed from said receptacle; anv air inlet into said gasification chamber above the fuel on said supporting means, and an exhaust duct leading from said gasification chamber above the fuel on said supporting means at a point substantially opposite said air inlet; and means to supply air under pressure through said inlet.

OLOF AXEL OHLSSON. 

